Levels of the male sex hormone testosterone are lower in infant boys conceived by intracytoplasmic sperm injection than in their naturally conceived counterparts. Intracytoplasmic sperm injection (ICSI) is an assisted fertility technique used to overcome male infertility. With ICSI, a single sperm is injected directly into a single egg. If successful fertilisation occurs, the embryo is then placed into the female to undergo development as usual. However, there has been a growing concern for the health of children conceived by assisted reproduction technologies. Researchers at Copenhagen University Hospital investigated whether a boy conceived by ICSI might inherit the impaired testicular function of his father. The study involved 125 boys conceived by ICSI, 120 conceived by in vitro fertilisation, also known as test tube fertilisation, and 933 naturally conceived boys. Standard growth measurements were taken at birth and at 3 months, and blood samples were also taken from more than half of the infants at 3 months. The results showed that testosterone levels in the blood were reduced in boys conceived by ICSI compared with the naturally conceived boys. Boys conceived by in vitro fertilisation, which is performed because of female infertility, also had normal testosterone levels. The findings suggest that there is an inherited impairment of testosterone-producing cells in ICSI-conceived boys. However, further research is warranted to explore the possible repercussions of these findings as ICSI is increasingly used to overcome male infertility.
Journal of Clinical Endocrinology and Metabolism,
July 2007